JPH0353344B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a curable printing ink that is cured by heat, ultraviolet light, ionizing radiation, etc. In recent years, with the development of printing technology, there has been a demand for faster printing speeds. Along with this, demands on the drying speed (curing speed) of printing ink are becoming increasingly strict. Conventionally, in high-speed printing, printed materials have been dried using direct flame or hot air as a means of accelerating drying.
The printing ink used in such heatset printing is dried by heating to evaporate 30 to 40% of the solvent contained therein. Therefore, in printing plants where heat setting is performed, a portion of the solvent vapor is discharged, which often poses a pollution problem. Therefore,
It is desired by those skilled in the art to have an ink that does not contain such volatile substances and can be dried by some means. Under these circumstances, there is a trend toward printing inks that dry without solvent evaporation, such as ultraviolet curable inks and thermosetting solvent-free inks, and several proposals have already been made. These curable coatings generally contain a curable resin having at least one radically polymerizable double bond and a curable diluent. Conventionally known curable diluents, that is, reactive unsaturated compounds, generally include alkyl (meth)acrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, and ethyl methacrylate, ethylene glycol diacrylate, and ethylene glycol dimethacrylate. ,
Polyethylene glycol di(meth)acrylate including diethylene glycol dimethacrylate, trimethylolproban triacrylate,
Trimethylolpropane trimethacrylate, tetramethylolmethane triacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethanetetraacrylate, tetramethylolmethanetetramethacrylate, phenyl glycol acrylate, phenyl glycol methacrylate, ethylene oxide adduct of bisphenol A ( (Meth)acrylates made by reacting meth)acrylic acid are known. These reactive unsaturated compounds are used as curable diluents for printing inks that are cured by the action of heat, ultraviolet rays, and ionizing radiation, but when used in offset printing, they cause so-called background smearing, and Adhesion is insufficient in printing on metal plates, aluminum foils, and various plastic films. The present inventor has found that when a (meth)acrylate having a tricyclodecane skeleton is used as a diluent in an offset printing ink, the above-mentioned background smearing phenomenon is less likely to occur and the adhesiveness is good. In addition, (meth)acrylic acid dihydrodicyclopentadienyl ester (Japanese Patent Publication No. 55-54313)
is known, and this curable diluent has advantages such as being hard to cause scumming and having good adhesive properties, but the curing speed is not necessarily fast and the curability is insufficient. The (meth)acrylate having a tricyclodecane skeleton according to the present invention has good curability, and
When used in offset printing, there is little occurrence of background smearing, and furthermore, it has good adhesion to various printing materials. That is, the following general formula [] (In the general formula, R is an organic residue having 1 to 3 carbon atoms, and n is an integer of 0 to 8.) Tricyclodecane dimethylol or a derivative thereof is esterified with acrylic acid and/or methacrylic acid. This is a curable printing ink using a curable diluent obtained by the above method and a curable resin having at least one radically polymerizable double bond. In addition, as a printing ink, the viscosity is too low to use only a curable diluent, so it does not have the hardness as a printing ink.
By using a curable resin, that is, a prepolymer, the viscosity of the printing ink can be adjusted and properties such as curability and printability can be imparted. Tricyclodecane dimethylol of the general formula [] or its derivatives according to the present invention include dicyclopentadiene and/or derivatives of dicyclopentadiene substituted with lower alkyl having 1 to 3 carbon atoms (for example, methyldicyclopentadiene). Formylation with carbon monoxide and hydrogen,
It is then obtained by hydrogenation. Note that commercially available products can also be used. Tricyclodecane dimethylol or one or a mixture of two or more of its derivatives and (meth)
The esterification reaction with acrylic acid is carried out using sulfuric acid or para-toluenesulfonic acid while blowing air at a temperature where the unsaturated groups of (meth)acrylic acid do not undergo thermal polymerization, preferably in the temperature range of 80°C to 120°C. This is preferably carried out using an acidic catalyst and a polymerization inhibitor such as hydroquinone or paramethoxyphenol. In performing this esterification reaction, the desired objective can be achieved by reacting 0.5 to 1 mole of acrylic acid and/or methacrylic acid per mole of hydroxyl group of general formula Preferably, a sufficient amount of acrylic acid and/or methacrylic acid is used to effect esterification. The curable diluent and curable resin obtained from the general formula [] according to the present invention are used in printing inks, and are particularly suitable as offset printing inks. To illustrate the composition of the curable printing ink, the product obtained from the general formula [] according to the present invention is
1 to 80% by weight Conventionally known curable resin having at least one radically polymerizable double bond
10-80% Pigment 0-65% by weight Sensitizer 0-20%. Curable resins include petroleum resin (meth)acrylate, epoxy (meth)acrylate,
It can be selected from various curable prepolymers such as alkyd (meth)acrylates and urethane-modified (meth)acrylates. In addition, in addition to these curable resins, in ionizing radiation curable resin compositions such as electron beams, other resins that are cured by electron beam irradiation, such as resins with double bonds and resins with halogen atoms, may be used in combination. I can do it. Furthermore, conventionally known curable diluents can also be used. For example, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol(meth)acrylate, 1,4
-butanediol di(meth)acrylate, 1,
6-hexanediol (meth)acrylate, alkyl (meth)acrylate (alkyl group with 1 to 18 carbon atoms), monohydric phenol or polyhydric phenol with alkylene oxide added to the hydroxyl group, and ester of acrylic acid or methacrylic acid. styrene, allyl alcohol ester, glycidyl (meth)acrylate, etc. can be used within the scope of the invention. The pigment is not particularly limited, and organic pigments and inorganic pigments used in printing inks and the like can be used. Of course, pigments may not be used. The sensitizer includes a photosensitizer and a thermal polymerization initiator, and conventionally known ones are used as necessary. In addition, fillers, solvents, etc. are added as necessary. The curable diluent obtained from the general formula [] according to the present invention can be used in thermal, ultraviolet, or ionizing radiation curable printing inks, and especially when used as a diluent for offset printing inks, it can be used as a diluent for conventional curable diluents. Compared to those using adhesives, the occurrence of scumming is significantly reduced, and the adhesion to metal plates, various plastic films, and aluminum foils is improved. Reference examples and examples will be described below. In the examples, "parts" indicate parts by weight. Reference example 1 Epicote 828 (manufactured by Ciel Chemical Co., Ltd., bisphenol A type epoxy resin) 71.7 parts, acrylic acid 28.3 parts
1 part, 0.1 part of hydroquinone, and 0.1 part of triethylenediamine were placed in a four-necked flask equipped with a stirrer, and while blowing air, they were reacted for 1.8 hours at 90 to 120°C to obtain a viscous resin with an acid value of 0.5. Reference Example 2 59.7 parts of tricyclodecane dimethylol, 40.3 parts of acrylic acid, 0.1 part of hydroquinone, 1.0 part of P-toluenesulfonic acid, and 10.0 parts of cyclohexane were placed in a four-neck flask equipped with a reflux stirrer, and while blowing air, cyclohexane was added. Under reflux, 80-100
The reaction was carried out at 95°C to 105°C for 13 hours, and when the acid value reached 5.0, cyclohexane was recovered at 95 to 105°C for 2 hours. The resulting product was a liquid with a viscosity of 2.9 poise/25°C. This is called curable diluent A. Reference example 3 Monomethyl tricyclodecane dimethylol 56.9
parts, 43.1 parts of methacrylic acid, 0.1 parts of hydroquinone,
P-toluenesulfonic acid 1.0 part, cyclohexane
10.0 parts were charged into a four-necked flask equipped with a reflux stirrer, and while blowing air, the reaction was carried out at 80 to 100°C under cyclohexane reflux for 14 hours. It took time to collect it. The resulting product was a liquid with a viscosity of 3.1 poise/25°C. Curing diluent B
shall be. Example 1 Curable diluents A and B obtained in Reference Examples 2 and 3,
Also, UV-curable offset printing was performed using ABPE-4 (diacrylate of ethylene oxide 4-mole adduct of bisphenol A manufactured by Shin-Nakamura Chemical Co., Ltd.) and acrylic acid dihydrodicyclopentanedienyl ester as a curable diluent. A red ink was prepared according to the formulation shown in Table 1, and its curability, offset suitability, and adhesion were tested. (A) Ink formulation

【table】

[Table] Note that the difference in the number of copies of each composition in Ink-1 to Ink-4 is due to the tack value.
This is because the flow value is the same as 10.0 and 16.5. The tack value is the value measured by an incometer, and is the tack value obtained 1 minute after placing 1.2 cc of ink on the incometer and rotating it at a water temperature of 30°C, a room temperature of 25°C, and a linear speed of 400 rpm. The flow value is a value measured using a parallel plate viscometer, and is expressed in millimeters as the radius of spread of the ink after 1 minute when 0.5 cc of ink is placed at a room temperature of 25°C and a constant load is applied. (B) Printing test and adhesion properties Each of the above red inks was printed on a sheet-fed offset printing machine (Heidelberg KORD-64 model) at 60 rpm.
After printing up to the 10,000th page, we looked at the UV curability of the printing ink, the occurrence of scumming, and the adhesion. Regarding ultraviolet curability, immediately after printing, the sample was placed on a conveyor at a distance of 10 cm under three 8KW high-pressure mercury lamps with an intensity of 80 W/cm, and exposed to ultraviolet rays.
Regarding adhesion, the printing materials indicated by A, B, and C in Table 2 were printed at a printing speed of 60 revolutions/minute using a sheet-fed printing machine using inks 1 to 4 in the same manner as in the curing test. After that, UV irradiation was performed at each conveyor speed shown in Table 2, and then a cellophane tape peeling test (crosscut test method) was performed. In addition, the adhesion evaluation values in Table 2, e.g.
10/100 indicates an adhesion rate of 10%. The test results were as shown in Table 2.

[Table] * Curing property indicates the speed at which the printed material passes under the conveyor ramp until it becomes tack-free.
In addition, in Table 2, compared to Ink-2, which uses acrylic acid dihydrodicyclopentadienyl ester as a curable diluent, Ink-3, which uses the same acrylic acid as a curable diluent, has superior curability. It is clear that there are. Example 2 Using the curable diluents A and B obtained in Reference Examples 2 and 3, an electron beam curable ink was prepared, and
The above ink was prepared using ABPE-4, acrylic acid dihydrodicyclopentadienyl ester.
Each of the obtained inks was irradiated with electron beams and their curability and adhesion were compared.

[Table] The ink viscosity was adjusted to be the same as in Example 1 using the measurement method shown in Example 1. Curability and Adhesion Using each of the above red inks, inks 1 to 4 were applied to the printing materials shown in Table 4 using an RI tester (ink spreading machine manufactured by Mei Seisakusho Co., Ltd.) with 0.4 cc of ink on the entire surface. After printing, electron beam irradiation was performed in a nitrogen atmosphere at an acceleration voltage of 160 KV, an electron beam current of 6 mA, and an irradiation distance of 10 cm using an electrocurtain (electron beam irradiation device manufactured by Energy Science Co., Ltd.) for curing. The adhesion test was conducted by cellophane tape peeling method (crosscut test method). The test results were as shown in Table 4.

[Table] *Electron beam curability is expressed as the amount of electron beam irradiation required for complete curing.
Example 3 Using curable diluents A and B obtained in Reference Examples 2 and 3, ABPE-4, and acrylic acid dihydrodicyclopentadienyl ester as curable diluents, thermosetting offset printing red ink was prepared. Table 5
It was prepared using the following formulation and tested for curability and adhesion. (A) Ink formulation

[Table] (B) Curability and adhesion The above red ink was printed with 0.4 cc of ink on the entire surface using an RI tester (ink spreading machine manufactured by Mei Seisakusho Co., Ltd.), and the thermosetting and adhesive properties were checked. Ta. Curability was evaluated by the heating time (thermal curing time) required for the printed matter to become tack-free using a 150°C hot air oven. Adhesion was evaluated by a cellophane tape peel test (cross cut test method) after curing at the heat curing time shown in the table below. The evaluation results of the test were as shown in Table 6.

【table】

Claims (1)

[Claims] 1. The following general formula (In the general formula, R is an organic residue having 1 to 3 carbon atoms, and n is an integer of 0 to 8.) Tricyclodecane dimethylol or a derivative thereof is esterified with acrylic acid and/or methacrylic acid. A curable printing ink characterized by using a curable diluent and a curable resin having at least one radically polymerizable double bond.